Circulatory assist devices are needed for immediate temporary treatment of acute myocardial infarction and for some postcardiotomy patients. Since more than 30 years ago, the efforts of a number of researchers and clinicians have resulted in the now widely used counterpulsation intra- aortic balloon pumping (IABP), which increases myocardial oxygen uptake and coronary perfusion, and reduces load on the heart and its oxygen demand. In 1973 a pneumatically-operated mechanical auxiliary ventricle (MAV), which operates on the same principle as an IABP, was implanted into the aorta of a patient during cardiopulmonary bypass, and it sustained him for 96 days. Since 1985, pneumatic artificial ventricles have been used as temporary assist and replacement devices prior to transplantation, and a wearable, battery-operated driver has recently been developed that can power a pneumatic VAD or TAH of ambulatory patients. The goal of the program is to develop a prototype of a portable intra- aortic balloon pumping machine for intra- and inter-hospital and vehicular patient transport. The market for a portable intra-aortic balloon operating device could be a sizable fraction of the total present market.